title: Pilot study of the effects of bariatric surgery and continuous positive airway pressure treatment on vascular function in obese subjects with obstructive sleep apnoea.
abstract: BACKGROUND
  The mechanisms by which obesity and obstructive sleep apnoea (OSA) may contribute to endothelial dysfunction are unclear.
  
  
  OBJECTIVE
  We sought to follow up a sample of obese subjects undergoing either bariatric surgery or continuous positive airway pressure (CPAP) therapy to treat OSA. We hypothesised improved vascular function with both therapeutic approaches, consistent with a reversible OSA effect on the circulation.
  
  
  METHODS
  Twenty-seven obese (BMI ≥30 kg/m(2)) subjects with OSA underwent either bariatric surgery without CPAP (n = 12, median BMI 43.7 kg/m(2) IQR 9.4) or CPAP (n = 15, median BMI 33.8 kg/m(2) IQR 6.6). Polysomnography and vascular testing (flow-mediated dilation of the brachial artery measured with high-resolution ultrasound, endothelium-dependent change in skin blood flow measured with laser Doppler flowmetry, and arterial stiffness measured with applanation tonometry) took place at baseline and after 6 months.
  
  
  RESULTS
  Both groups showed significant improvements in the apnoea-hypopnea index and overnight oxygen saturation. Endothelium-dependent microvascular reactivity was 45.6% (IQR 37.5) at baseline in the CPAP group, which increased to 69.1% (IQR 62.3) post-treatment (P < 0.05). No significant changes were observed in the surgery group, despite significant weight loss (post-surgery BMI 32.7 kg/m2 IQR 8.6 (P < 0.01); no change in BMI was observed in the CPAP group. There were no significant changes in brachial artery flow-mediated dilation in either group.
  
  
  CONCLUSIONS
  This pilot study demonstrates that 6 months of CPAP may be sufficient to improve endothelium-dependent microvascular reactivity, while substantial surgically induced weight loss did not result in improvements. Further research should be directed towards comparative effectiveness trials using these novel surrogate outcomes, as well as hard cardiovascular outcomes.
authors.affiliation: Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA, USA. jpbakker@partners.org
authors.forename: J P
authors.initials: JP
authors.lastname: Bakker
authors.forename: J S
authors.initials: JS
authors.lastname: Balachandran
authors.forename: F
authors.initials: F
authors.lastname: Tecilazich
authors.forename: P N
authors.initials: PN
authors.lastname: Deyoung
authors.forename: E
authors.initials: E
authors.lastname: Smales
authors.forename: A
authors.initials: A
authors.lastname: Veves
authors.forename: A
authors.initials: A
authors.lastname: Malhotra
mesh_terms: D000328:Adult; D050110:Bariatric Surgery / Q000379:methods*; D001783:Blood Flow Velocity / Q000502:physiology*; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D003430:Cross-Sectional Studies; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy*; D010865:Pilot Projects; D017286:Polysomnography / Q000379:methods; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome
keywords: cardiovascular; endothelium; microvascular; obstructive sleep apnoea